Verify HTTP paths both in incoming requests and in config file
This merge request adds HTTP paths validation (both in incoming requests and configuration file). Now BIND will fail loading a configuration file which contains wrong HTTP paths, e.g.:
20-May-2021 14:07:43.032 loading configuration from '/home/artem/projects/isc/open/bind9/../doh-test.conf' 20-May-2021 14:07:43.032 /home/artem/projects/isc/open/bind9/../doh-test.conf:10: quoted string is not a valid absolute HTTP path near '"/dns-query?dns="' 20-May-2021 14:07:43.042 loading configuration: unexpected token 20-May-2021 14:07:43.042 exiting (due to fatal error)
Initially separated from !5036 (merged).